Charged particle beam apparatus

ABSTRACT

A charged particle beam apparatus includes a database that stores a to-be-used-in-calculation device model for use in estimation of a circuit of a sample and an optical condition under which a charged particle beam is applied to the sample, a charged particle beam optical system that controls the beam applied to the sample under the optical condition, a detector that detects secondary electrons emitted from the sample excited by the application of the beam and outputs a detection signal based on the secondary electrons, and a computing unit that generates a to-be-used-in-computation netlist based on the to-be-used-in-calculation device model, estimates a first application result when the beam is applied to the sample based on the to-be-used-in-computation netlist and the optical condition, and compares the first application result with a second application result when the beam is applied to the sample based on the optical condition.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a charged particle beam apparatus.

2. Description of the Related Art

Charged particle beam apparatuses such as electron microscopes and ionmicroscopes are used in observation of various samples having a finestructure. For example, for the purpose of process control on amanufacturing process of semiconductor devices, a scanning electronmicroscope that is one of the charged particle beam apparatuses is usedin measurement of dimensions of a semiconductor device pattern formed ona semiconductor wafer serving as a sample, defect inspection of thesemiconductor device pattern, or the like.

A method known as one of the sample analysis methods using an electronmicroscope is to form a potential contrast image from secondaryelectrons obtained through application of an electron beam to a sampleand evaluate electrical resistance of an element formed on the sample onthe basis of analysis of the potential contrast image.

For example, JP 2003-100823 A discloses a method for identifying adefect by calculating an electrical resistance value from a potentialcontrast. JP 2008-130582 A discloses a method for predictingcharacteristics of a defect in an electric resistance value or the likeby creating, as an equivalent circuit, a netlist that describesinformation on electrical characteristics and connectivity of circuitelements from a potential contrast.

SUMMARY OF THE INVENTION

For inspection and measurement of semiconductor devices, it is requiredthat a defect in electrical characteristics of the devices in amanufacturing process be detected. However, with the techniquesdisclosed in JP 2003-100823 A and JP 2008-130582 A, it is difficult toestimate the electrical characteristics with consideration given tointeractions between a plurality of the devices using design data andinspection measurement data. In addition, it takes a lot of time andeffort to convert the design data, and it takes a long time to estimatethe electrical characteristics.

Therefore, an object of the present invention is to provide a chargedparticle beam apparatus that estimates, in a short time, electricalcharacteristics with consideration given to interactions between aplurality of devices.

The following is a brief description of the summary of a primary aspectof the invention disclosed herein.

A charged particle beam apparatus according to the primary aspect of thepresent invention includes a database configured to store ato-be-used-in-calculation device model for use in estimation of acircuit of a sample and an optical condition under which a chargedparticle beam is applied to the sample, a charged particle beam opticalsystem configured to control the charged particle beam applied to thesample under the optical condition, a detector configured to detectsecondary electrons emitted from the sample excited by the applicationof the charged particle beam and output a detection signal based on thesecondary electrons, and a computing unit configured to generate ato-be-used-in-computation netlist on the basis of theto-be-used-in-calculation device model, estimate a first applicationresult when the charged particle beam is applied to the sample on thebasis of the to-be-used-in-computation netlist and the opticalcondition, and compare the first application result with a secondapplication result when the charged particle beam is applied to thesample on the basis of the optical condition.

The following is a brief description of an effect obtained by theprimary aspect of the invention disclosed herein.

That is, according to the primary aspect of the present invention, it ispossible to estimate, in a short time, electrical characteristics withconsideration given to interactions between a plurality of devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an example of a structure of acharged particle beam apparatus according to a first embodiment of thepresent invention;

FIG. 2 is a block diagram showing an example of the structure of thecharged particle beam apparatus according to the first embodiment of thepresent invention;

FIG. 3 is a diagram showing a to-be-used-in-calculation device modelstored in a database;

FIG. 4 is a diagram showing an optical condition stored in a database;

FIG. 5 is a flowchart showing an example of a circuit estimation methodfor a sample;

FIG. 6 is a diagram showing an example of a to-be-used-in-calculationdevice model selection screen;

FIG. 7 is a diagram showing an example of an optical condition selectionscreen;

FIG. 8 is a diagram showing an example of a result display screen aftercircuit estimation; and

FIGS. 9A to 9C are diagrams showing another example of the resultdisplay screen after circuit estimation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings. Each of the embodimentsdescribed below is an example for practicing the present invention andis not intended to limit the technical scope of the present invention.Note that, in the embodiments, components having the same function aredenoted by the same reference numerals, and repeated description of suchcomponents will be omitted unless particularly necessary.

First Embodiment <Structure of Charged Particle Beam Apparatus>

FIG. 1 is a schematic diagram showing an example of a structure of acharged particle beam apparatus according to a first embodiment of thepresent invention. FIG. 2 is a block diagram showing an example of thestructure of the charged particle beam apparatus according to the firstembodiment of the present invention. As shown in FIGS. 1 and 2, acharged particle beam apparatus 1 includes a charged particle beamapparatus main body 10, a computer 30, and an input and output part 50.

<Charged Particle Beam Apparatus Main Body>

The charged particle beam apparatus main body 10 has a structure where alens barrel 10A is mounted on a sample chamber 10B in which a sample 23to be inspected is held, and a controller 11 is disposed outside thelens barrel 10A and the sample chamber 10B. In the lens barrel 10A, anelectron source (charged particle source) 12 that emits an electron beam(charged particle beam), a pulsed electron generator 19 that pulses theelectron beam, a diaphragm 13 that regulates an application current ofthe electron beam thus emitted, a deflector 14 that controls anapplication direction of the electron beam, an objective lens 18 thatcauses the electron beam to converge, and the like are held. Althoughnot shown, in the lens barrel 10A, a condenser lens is provided. Notethat, unless the electron beam is pulsed, the pulsed electron generator19 need not be provided.

Further, in the lens barrel 10A, a detector 25 that detects secondaryelectrons emitted from the sample 23 excited by the application of theelectron beam, and outputs a detection signal based on the secondaryelectrons. The detection signal is used in generation of a scanningelectron microscopy (SEM) image, measurement of the size of the sample23, measurement of electrical characteristics, and the like.

In the sample chamber 10B, a stage 21, the sample 23, and the like areheld. The sample 23 is mounted on the stage 21. Examples of the sample23 include a semiconductor wafer including a plurality of semiconductordevices, and an individual semiconductor device. The stage 21 isprovided with a stage drive mechanism (not shown) and is movable withinthe sample chamber 10B under the control of the controller 11.

The controller 11 is a functional block responsible for controllingcomponents of the charged particle beam apparatus main body 10. Thecontroller 11 controls the operation of each component such as theelectron source 12, the pulsed electron generator 19, the diaphragm 13,the deflector 14, and the objective lens 18 under, for example, anoptical condition input from the computer 30 and the like. As describedabove, the controller 11, the electron source 12, the pulsed electrongenerator 19, the diaphragm 13, the deflector 14, the objective lens 18,and the like constitute a charged particle beam optical system BS thatcontrols the electron beam.

Further, the controller 11 moves the sample 23 to a predeterminedposition by controlling the stage drive mechanism under, for example,the optical condition input from the computer 30 and the like. Further,the controller 11 controls a power supply or control signal supply tothe detector 25 to control a process of detecting the secondaryelectrons performed by the detector 25.

The controller 11 is implemented with a program executed by a processorsuch as a CPU. Further, the controller 11 may be configured by, forexample, a field-programmable gate array (FPGA) or an applicationspecific integrated circuit (ASIC).

<Computer>

As shown in FIG. 1, the computer 30 includes a computing unit 31 and astorage device 41. The computing unit 31 is a functional blockresponsible for estimating a circuit (or equivalent circuit) of thesample 23. As shown in FIG. 2, for example, the computing unit 31includes a to-be-used-in-computation netlist generator 32, an electronbeam application result estimation computing unit 33, and a comparator34. The to-be-used-in-computation netlist generator 32 generates ato-be-used-in-computation netlist corresponding to the sample 23 on thebasis of a to-be-used-in-calculation device model to be described laterand the optical condition. Further, the to-be-used-in-computationnetlist generator 32 also updates the to-be-used-in-computation netliston the basis of a comparison result from the comparator 34.

The electron beam application result estimation computing unit 33estimates an electron beam application result on the basis of theto-be-used-in-computation netlist generated by theto-be-used-in-computation netlist generator 32. The comparator 34compares the electron beam application result estimated by the electronbeam application result estimation computing unit 33 (first applicationresult) with an actually measured electron beam application result(second application result).

In addition to these processes, the computing unit 31 performs a processof displaying the estimated electron beam application result, themeasured electron beam application result, and a netlist identified forthe sample 23 (hereinafter, also referred to as “estimated netlist”), aprocess of generating an inspection image (SEM image or the like) of thesample 23 on the basis of the detection signal, measuring the size ofthe sample 23, and measuring the electrical characteristics of thesample 23, and the like.

The computing unit 31 may be implemented with a program executed by aprocessor such as a CPU, as in the controller 11, or alternatively, maybe configured by an FPGA, an ASIC, or the like.

The storage device 41 includes a database 42, an optical conditionstorage section 43, a to-be-used-in-computation netlist storage section44, an electron beam application result storage section 45, and anestimated application result storage section 46. The database 42 storesto-be-used-in-calculation device models (for example, DM1 and DM2) andoptical conditions (for example, LC1 and LC2) used in generation of theto-be-used-in-computation netlist. Note that theto-be-used-in-calculation device models include a model representing adefect in a device including the sample.

A user may operate the input and output part 50 to register theto-be-used-in-calculation device models and the optical conditions, oralternatively, the computer 30 may be connected to an external device toreceive the to-be-used-in-calculation device models from the externaldevice. The database 42 stores the to-be-used-in-calculation devicemodels and the optical conditions, for example, in the form of a look uptable (LUT).

FIG. 3 is a diagram showing an example of the to-be-used-in-calculationdevice model stored in the database. A unique ID 42 a (for example, DM1and DM2) is assigned to each of to-be-used-in-calculation device models,and each of the to-be-used-in-calculation device models is identified bythe ID 42 a. Each of the to-be-used-in-calculation device modelsincludes pieces of information such as a model 42 b, a mathematicalexpression 42 c, a parameter type 42 d, a parameter value 42 e, andother data 42 f. Note that, in each of the to-be-used-in-calculationdevice models, only some of the pieces of information may be defined.

The model 42 b is information that defines a circuit of the device.Information defining a circuit such as an RC parallel circuit isregistered as the model 42 b. Alternatively, a waveform model of thedevice or the like may be registered as the model 42 b. The mathematicalexpression 42 c includes information that defines electricalcharacteristics of the device that cannot be expressed by the circuit.The parameter type 42 d is information that defines a type of circuitelement included in the device, such as resistance (R) or capacitance(C). The parameter value 42 e is associated with each element of theparameter type 42 d and is information that defines a value of thecircuit element associated with the parameter type 42 d. For example,when the resistance (R) and the capacitance (C) are registered as theparameter types, their respective parameter values are a resistancevalue and a capacitance value. The other data 42 f includes informationsuch as a shape of the device or physical properties of the device.

FIG. 4 is a diagram showing the optical condition stored in thedatabase. A unique ID 42 g (for example, LC1 and LC2) is assigned toeach of the optical conditions, and each of the optical conditions isidentified by the ID 42 g. Each of the optical conditions includespieces of information such as application energy 42 h, an applicationcurrent 42 i, a scan condition 42 j, a parameter value 42 k, and otherdata 421. Note that, in each of the optical conditions, only some of thepieces of information may be defined.

The application energy 42 h is information that defines energy of thecharged electron beam applied to the sample. The application energyincludes, for example, an electron accelerating voltage or retardingvoltage. Herein, the retarding voltage refers to a voltage thatdecelerates the electron beam (charged particle beam) immediately beforethe sample by applying the voltage to the sample. The applicationcurrent 42 i is information that defines the current of the electronbeam. The application current may also be referred to as a probecurrent.

The scan condition 42 j is information that defines an electron beamapplication method. The scan condition 42 j includes, for example,pieces of information such as a scan speed (scanning speed) and ascanning interval. The parameter value 42 k is information that definesa parameter associated with the application of the electron beam. Theparameter value 42 k includes, for example, pieces of information suchas a magnification, an aperture angle, and a working distance. The otherdata 421 includes the other pieces of information associated with acorresponding optical condition. Further, the other data 421 may includean electron beam pulse conversion condition (modulation condition).

The electron beam pulse conversion condition includes, for example, apulse width, a duty cycle, a frequency, any pattern in which the pulsewidth and the duty cycle change with time, and the like.

Note that the optical condition may be referred to as an electronoptical condition, for example.

The optical condition storage section 43 stores a selected electron beamoptical condition. The to-be-used-in-computation netlist storage section44 stores the to-be-used-in-computation netlist generated or updated bythe to-be-used-in-computation netlist generator 32. The electron beamapplication result storage section 45 stores the electron beamapplication result of the sample 23 actually measured on the basis ofthe detection signal output from the detector 25. The electron beamapplication result stored in the electron beam application resultstorage section 45 may be the detection signal output from the detector25, the SEM image based on the detection signal, or the like. Theestimated application result storage section 46 stores the electron beamapplication result of the sample 23 estimated by the electron beamapplication result estimation computing unit 33.

The storage device 41 is configured by, for example, a non-volatilememory such as a flash memory. Further, some of the storage sectionsincluded in the storage device 41 may be configured by a volatile memorysuch as a dynamic random access memory (DRAM) or a static random accessmemory (SRAM). Each of the storage sections included in the storagedevice 41 may be provided as a separate device, or alternatively, as aseparate storage area defined in one storage device.

<Input and Output Part>

The input and output part 50 is a functional block responsible foroperations on the charged particle beam apparatus 1, selection of theto-be-used-in-calculation device model or optical condition, display ofthe electron beam application result and estimated application result ofthe sample 23, and the estimated netlist, and the like. The input andoutput part 50 includes a display 60 of, for example, a touch screentype. On the display 60, for example, an operation panel of the chargedparticle beam apparatus 1, a selection section 51 for use in selectionof the to-be-used-in-calculation device model or optical condition, anestimated netlist 52, an estimated application result 53, an electronbeam application result 54, and the like are displayed.

<Circuit Estimation Method for Sample>

Next, a circuit estimation method for the sample 23 will be described.According to the present embodiment, a netlist of the sample isestimated on the basis of the to-be-used-in-computation netlistgenerated from the to-be-used-in-calculation device model and acomparison between the electron beam application result estimated usingthe optical condition and the actual electron beam application resultbased on the optical condition. FIG. 5 is a flowchart showing an exampleof the circuit estimation method for the sample. In the example shown inFIG. 5, the circuit estimation for the sample is made in steps S10 toS130.

Once the circuit estimation process is initiated, theto-be-used-in-calculation device model is selected (step S10). FIG. 6 isa diagram showing an example of a to-be-used-in-calculation device modelselection screen. On the to-be-used-in-calculation device modelselection screen 61 shown in FIG. 6, for example, a list 61 a of theto-be-used-in-calculation device models registered in the database 42and a selection determination button 61 e are shown. The list 61 aincludes an ID display field 61 b of each of the registeredto-be-used-in-calculation device model, a to-be-used-in-calculationdevice model selection field 61 c, and a details display field 61 d of acorresponding to-be-used-in-calculation device model.

From the to-be-used-in-calculation device model selection screen 61displayed on the display 60, the user selects ato-be-used-in-calculation device model having a circuit that is the sameas or similar to the sample 23 to be measured. In the presentembodiment, one to-be-used-in-calculation device model is selected.Specifically, the user checks a check box corresponding to ato-be-used-in-calculation device model to be selected, and then touchesthe selection determination button 61 e to finalize the selection of theto-be-used-in-calculation device model. FIG. 6 shows a case where ato-be-used-in-calculation device model assigned the ID “DM1” isselected. The to-be-used-in-calculation device model thus selected issent to the to-be-used-in-computation netlist generator 32 shown in FIG.2.

In step S20, the to-be-used-in-computation netlist generator 32generates a to-be-used-in-computation netlist on the basis of theto-be-used-in-calculation device model selected by the user. Forexample, the method for generating the to-be-used-in-computation netlistis not limited to a method by which the to-be-used-in-computationnetlist generator 32 combines any of the model 42 b, the parameter type42 d, the shape of the device, or the physical properties of the deviceand the parameter value 42 e included in the selectedto-be-used-in-calculation device model to generate theto-be-used-in-computation netlist.

In step S30, an optical condition is selected. FIG. 7 is a diagramshowing an example of an optical condition selection screen. On anoptical condition selection screen 62 shown in FIG. 7, for example, alist 62 a of the optical conditions registered in the database 42 and aselection determination button 62 e are displayed. The list 62 aincludes an ID display field 62 b of each of the registered opticalcondition, an optical condition selection field 62 c, and a detailsdisplay field 62 d of a corresponding optical condition.

The user selects a desired optical condition from the optical conditionselection screen 62 displayed on the display 60. More specifically, theuser checks a checkbox corresponding an optical condition to beselected, and then touches the selection determination button 62 e tofinalize the selection of the optical condition. FIG. 7 shows a casewhere an optical condition assigned the ID “LC2” is selected. Theoptical condition thus selected is stored in the optical conditionstorage section 43 shown in FIG. 2.

Note that, in step S10, when the selection determination button 61 e istouched to finalize the selection of the to-be-used-in-calculationdevice model, the optical condition selection screen 62 may be displayedafter the to-be-used-in-calculation device model selection screen 61 isdeleted. Further, when the selection of the to-be-used-in-calculationdevice model is finalized, the optical condition selection screen 62 maybe displayed superimposed on the to-be-used-in-calculation device modelselection screen 61. The optical condition selection screen 62 may beprovided with a button that causes the to-be-used-in-calculation devicemodel selection screen 61 to be displayed again.

Further, for the settings of the optical condition, the electron beampulse conversion condition (modulation condition) is used as necessary.The electron beam pulse conversion condition may be used together withthe optical condition, or the electron beam pulse conversion conditionalone may be set as the optical condition.

In step S40, the electron beam is applied to the sample 23 under theoptical condition selected in step S30. The optical condition stored inthe optical condition storage section 43 is sent to the controller 11 ofthe charged particle beam apparatus main body 10. The controller 11controls each component of the charged particle beam optical system BSto apply the electron beam to the sample 23 under the optical conditionthus received. When the electron beam is applied to the sample 23, thesecondary electrons are emitted from the sample 23. When detecting thesecondary electrons emitted from the sample 23, the detector 25 outputsa predetermined detection signal in accordance with the number of thesecondary electrons, application energy, or the like to the computer 30(computing unit 31).

In step S50, an actual electron beam application result of the sample 23is stored. The computing unit 31 may store, for example, the detectionsignal (signal waveform) output from the detector 25 in the electronbeam application result storage section 45 as the electron beamapplication result. Further, the computing unit 31 may generate aninspection image (SEM image or the like) on the basis of the detectionsignal and store the inspection image in the electron beam applicationresult storage section 45 as the electron beam application result.Further, the computing unit 31 may measure an electrical charge carriedby the sample 23 on the basis of the detection signal and store theelectrical charge thus measured in the electron beam application resultstorage section 45. Further, the computing unit 31 may detect brightnessof the inspection image or brightness of each pixel of the inspectionimage and store the brightness thus detected in the electron beamapplication result storage section 45.

In step S60, the to-be-used-in-computation netlist generated in step S20is stored in the to-be-used-in-computation netlist storage section 44.Note that step S20 and step S60 are separately shown in FIG. 5, but theprocess of step S60 may be executed in step S20.

In step S70, the electron beam application result is estimated. Theelectron beam application result estimation computing unit 33 estimatesthe electron beam application result of the sample 23 on the basis ofthe to-be-used-in-computation netlist stored in theto-be-used-in-computation netlist storage section 44 and the opticalcondition stored in the optical condition storage section 43. Items ofthe electron beam application result to be estimated here are the sameas measurement items in step S50, and include, for example, thedetection signal (signal waveform) output from the detector 25, theelectrical charge, the inspection image, the brightness of theinspection image, the brightness of each pixel of the inspection image,and the like.

In step S80, the electron beam application result estimated in step S70is stored in the estimated application result storage section 46.

In step S90, the actual electron beam application result and theestimated electron beam application result are compared. The comparator34 compares the actual electron beam application result and theestimated electron beam application result for each item of the electronbeam application result. The comparator 34 compares the detectionsignals for each electron beam application region or each pixel of theinspection image, for example. The comparator 34 also compares, forexample, the electrical charge, the inspection image, the brightness ofthe inspection image, the brightness of each pixel of the inspectionimage, and the like. The comparator 34, for example, digitizes theseapplication results and calculates a difference between the actualelectron beam application result and the estimated electron beamapplication result for each item to generate a comparison result. Notethat the comparator 34 may compare all of these items, or may compareonly some of the items.

In step S100, a determination is made as to whether the actual electronbeam application result and the estimated electron beam applicationresult coincide with each other on the basis of the comparison resultcalculated in step S90. For example, when a value of the comparisonresult is “0”, the comparator 34 determines that these applicationresults coincide with each other. On the other hand, when the value ofthe comparison result is not “0”, the comparator 34 determines thatthese comparison results differs from each other. Note that, inpractice, these application results rarely coincide with each other;therefore, it is necessary to take a measurement error within apredetermined range into account.

This allows the comparator 34 to determine that the application resultscoincide with each other when the value of the comparison result isequal to or less than a predetermined threshold. The predeterminedthreshold is defined for each item. Note that when the comparison ismade for a plurality of items, the comparator 34 may determine thatthese application results coincide with each other only when thecomparison results for all the items are equal to or less than therespective thresholds, or alternatively, may determine that theseapplication results coincide with each other when the comparison resultsfor at least a predetermined number of items are equal to or less thanthe respective thresholds.

When the comparator 34 determines in step S100 that these electron beamapplication results differ from each other (No), the process of stepS110 is executed.

In step S110, the to-be-used-in-computation netlist is updated. Thecomparator 34 sends the comparison result to theto-be-used-in-computation netlist generator 32, and theto-be-used-in-computation netlist generator 32 updates theto-be-used-in-computation netlist, for example. Theto-be-used-in-computation netlist generator 32 changes, on the basis ofthe comparison result, a parameter value used in generation of the lastto-be-used-in-computation netlist, and generates ato-be-used-in-computation netlist using the parameter value thuschanged, for example. As described above, the to-be-used-in-computationnetlist generator 32 updates the to-be-used-in-computation netlist. Atthis time, the to-be-used-in-computation netlist generator 32 may changethe parameter value on the basis of the comparison results for aplurality of items. Further, the to-be-used-in-computation netlistgenerator 32 may preset a parameter whose parameter value is variableand update the to-be-used-in-computation netlist while changing theparameter value of only such a variable parameter.

The updated to-be-used-in-computation netlist is stored in theto-be-used-in-computation netlist storage section 44 (step S60). Theelectron beam application result is estimated again using the updatedto-be-used-in-computation netlist and the optical condition (step S70),and the estimated electron beam application result is stored in theestimated application result storage section 46 (step S80). Then, theelectron beam application result estimated using the updatedto-be-used-in-computation netlist and the actual electron beamapplication result are compared again (step S90).

The processes of steps S60 to S110 are repeatedly executed until theestimated electron beam application result and the actual electron beamapplication result coincide with each other. Note that theto-be-used-in-computation netlist may be updated in theto-be-used-in-computation netlist storage section 44. In this case, theprocesses of steps S70 to S110 are repeatedly executed until theestimated electron beam application result and the actual electron beamapplication result coincide with each other.

On the other hand, in step S100, when the comparator 34 determines thatthese electron beam application results coincide with each other (Yes),the process of step S120 is executed. In step S120, the computing unit31 (comparator 34) determines that the to-be-used-in-computation netliststored in the to-be-used-in-computation netlist storage section 44 canbe identified as a netlist describing the circuit of the sample 23, andstores this to-be-used-in-computation netlist in the estimated netliststorage section 47 as an estimated netlist. Further, in addition to theestimated netlist, a correspondence table that associates a position ofa plug electrode in the inspection image with each node in the estimatednetlist may be stored in the estimated netlist storage section 47.

In step S130, the estimation result and measurement result are output tothe input and output part 50. For example, the estimated netlist storedin the estimated netlist storage section 47, the estimated electron beamapplication result stored in the estimated application result storagesection 46, the actual electron beam application result stored in theelectron beam application result storage section 45 are output to theinput and output part 50 and displayed on the display 60.

FIG. 8 is a diagram showing an example of a result display screen aftercircuit estimation. As shown in FIG. 8, a to-be-used-in-calculationdevice model designation section 71, an estimated result display section72, an estimated electron beam application result display section 73,and an electron beam application result display section 74 are eachdisplayed as a result display screen 70.

In the to-be-used-in-calculation device model designation section 71,details of the selected to-be-used-in-calculation device model, theselected optical condition, and the like are displayed. For example, theuser can confirm the details of the selected to-be-used-in-calculationdevice model and optical condition by touching theto-be-used-in-calculation device model designation section 71. In theestimated result display section 72, each parameter value used ingeneration of the estimated netlist is displayed. Further, in theestimated result display section 72, information on whether theparameter is variable may be displayed together with the parametervalue.

In the estimated electron beam application result display section 73,the estimated electron beam application result is displayed. In theestimated electron beam application result display section 73, a graphin which the horizontal axis represents the electron beam applicationcondition (optical condition), and the vertical axis represents thebrightness (brightness) is displayed. Specifically, in the estimatedelectron beam application result display section 73, electron beamapplication results estimated for a plurality of nodes (plug electrodes)are displayed. Note that, in the estimated electron beam applicationresult display section 73, not only the estimated result using theestimated netlist but also the estimated result using theto-be-used-in-computation netlist before being identified may bedisplayed.

In the electron beam application result display section 74, the actuallymeasured electron beam application result is displayed. In the electronbeam application result display section 74, a graph in which thehorizontal axis represents the electron beam application condition andthe vertical axis represents the brightness (brightness) is displayed inthe same manner. In the electron beam application result display section74, electron beam application results for a plurality of nodes aredisplayed.

Note that the graphs displayed in the estimated electron beamapplication result display section 73 and the electron beam applicationresult display section 74 can be configured as desired. For example, agraph in which the vertical axis represents the amount of detectedsecondary electrons may be displayed. Further, in each of the estimatedelectron beam application result display section 73 and the electronbeam application result display section 74, the waveform of thedetection signal, the inspection image, and the like may be displayed.

Further, the estimated electron beam application result display section73 and the electron beam application result display section 74 may becombined such that the estimated result and the measured result aredisplayed together.

FIGS. 9A to 9C are diagrams showing another example of the resultdisplay screen after circuit estimation. In the result display screen70, not only the sections shown in FIG. 8, but also images shown inFIGS. 9A to 9C may be displayed, for example. FIG. 9A is an imagerepresenting an inspection image in which coordinates of plug electrodesare additionally illustrated. FIG. 9B is an estimated netlist. FIG. 9Cis a correspondence table that associates each of the positions of theplug electrode in the inspection image with a corresponding node in theestimated netlist. Further, a circuit diagram based on the estimatednetlist may be displayed in the result display screen 70.

Note that processes such as the generation of theto-be-used-in-computation netlist, the measurement through applicationof the electron beam, and the estimation of the electron beamapplication result have been described in order with reference to FIG.5, but these processes may be executed in parallel. For example, themeasurement through application of the electron beam may be executed atthe same time as the generation of the to-be-used-in-computation netlistand the estimation of the electron beam application result.

Further, artificial intelligence (AI) based on a method such as machinelearning or deep learning may be applied to processes such as theestimation of the electron beam application result in step S70, theupdate of the to-be-used-in-computation netlist in step S110, and thelike.

Main Effects of the Present Embodiment

According to the present embodiment, the to-be-used-in-computationnetlist is generated on the basis of the to-be-used-in-calculationdevice model, and the electron beam application result when the electronbeam is applied to the sample is estimated on the basis of theto-be-used-in-computation netlist and the optical condition. Further,the estimated electron beam application result is compared with theelectron beam application result when the electron beam is applied tothe sample 23 on the basis of the optical condition.

This configuration eliminates the need of converting an external netlistinput from the outside into the to-be-used-in-computation netlist, andthereby allows the electrical characteristics of the sample 23 to beestimated in a short time, increasing the throughput. The configurationfurther allows the electrical characteristics and circuit of the sample23 to be freely estimated without being affected by the configuration ofthe external netlist, and thereby allows the electrical characteristicsto be estimated with consideration given to interactions between aplurality of devices.

Further, according to the present embodiment, when the estimatedelectron beam application result and the actual electron beamapplication result differ from each other, the to-be-used-in-calculationdevice model is updated. Specifically, the computing unit 31 updates theto-be-used-in-computation netlist by changing the parameter valueincluded in the to-be-used-in-calculation device model and creating theto-be-used-in-computation netlist again using the changed parametervalue. This configuration makes it possible to update theto-be-used-in-computation netlist while suppressing the computationamount and to thereby suppress a load on the computing unit 31.

Further, according to the present embodiment, the electron beamapplication result includes any one of the detection signal, theinspection image based on the detection signal, the brightness of theinspection image, or the brightness of each pixel in the inspectionimage. This configuration makes it is possible to collate applicationresults with various forms based on the detection signal.

Further, according to the present embodiment, theto-be-used-in-calculation device model includes a model representing adefect in the sample 23. This configuration makes it possible to easilydetect a defect (manufacturing defect) in the sample 23 and to therebyincrease accuracy in circuit estimation.

Further, according to the present embodiment, theto-be-used-in-calculation device model includes any one of a modeldefining a circuit of a device, a mathematical expression definingelectrical characteristics of the device, a shape of the device, orphysical properties of the device. This configuration makes it possibleto estimate the circuit of the sample 23 from not only the circuitconfiguration but also the electrical characteristics, the shape, thephysical properties, and the like and to thereby increase accuracy incircuit estimation.

Further, according to the present embodiment, the computing unit 31generates a correspondence table that associates the position of theplug electrode in the inspection image with each node in the identifiedto-be-used-in-computation netlist (estimated netlist). Thisconfiguration makes the correspondence between the netlist and theinspection image clear.

Further, according to the present embodiment, the electron beamapplication result is estimated on the basis of the optical conditionand the electron beam pulse conversion condition. This configurationmakes it is possible to increase accuracy in estimation of theelectrical characteristics of the sample 23 with the electron beam thatchanges in a complicated manner.

Second Embodiment

Next, a second embodiment will be described. According to the presentembodiment, a plurality of to-be-used-in-calculation device models andone optical condition are used, and application results are compared foreach of the to-be-used-in-calculation device models. An apparatusstructure according to the present embodiment is the same as thestructure shown in FIGS. 1 to 4.

<Circuit Estimation Method for Sample>

Next, a circuit estimation method according to the present embodimentwill be described. According to the present embodiment, the circuitestimation is also performed according to the flow shown in FIG. 5. Thefollowing mainly describes processes different from the processesaccording to the first embodiment.

In step S10, a plurality of to-be-used-in-calculation device models areselected. For example, the user selects the plurality ofto-be-used-in-calculation device models by checking the check boxes ofthe plurality of to-be-used-in-calculation device models on theto-be-used-in-calculation device model selection screen 61 shown in FIG.6 and touching the selection determination button 61 e.

In step S20, the to-be-used-in-computation netlist for each of theselected plurality of to-be-used-in-calculation device models isgenerated. Then, in step S60, the to-be-used-in-computation netlistsgenerated in step S20 are stored in the to-be-used-in-computationnetlist generator 32.

In step S70, the electron beam application result is estimated usingeach of the to-be-used-in-computation netlists stored in theto-be-used-in-computation netlist generator 32. In step S80, a pluralityof electron beam application results estimated in step S70 are stored inthe estimated application result storage section 46.

In step S90, the actual electron beam application result and theestimated plurality of electron beam application results are compared.The comparator 34 generates a comparison result for each of theestimated electron beam application results. In step S100, adetermination is made as to whether the actual electron beam applicationresult and each of the estimated electron beam application resultscoincide with each other.

When a determination is made in step S100 that the actual electron beamapplication result coincides with none of the estimated electron beamapplication results (No), all the to-be-used-in-computation netlists areupdated in step S110. On the other hand, when a determination is madethat the actual electron beam application result coincides with any oneof the estimated electron beam application results (Yes), the process ofstep S120 is executed.

In step S120, the to-be-used-in-computation netlist corresponding to theestimated electron beam application result that coincides with theactual electron beam application result is identified as a netlistdescribing the sample 23. The identified to-be-used-in-computationnetlist is stored in the estimated netlist storage section 47 as anestimated netlist.

In step S130, the estimation results for the plurality ofto-be-used-in-calculation device models may be displayed on the resultdisplay screen 70.

Main Effects of the Present Embodiment

According to the present embodiment, the following effects can beobtained in addition to the effects of the above-described embodiment.According to the present embodiment, a plurality ofto-be-used-in-calculation device models and one optical condition areused, and, for each of the to-be-used-in-calculation device models, theestimated electron beam application result and the actual electron beamapplication result are compared. This configuration makes it possible toestimate, in a short time, the circuit and electrical characteristics ofthe sample 23 having a complicated structure.

Third Embodiment

Next, a third embodiment will be described. According to the presentembodiment, one to-be-used-in-calculation device model and a pluralityof optical conditions are used, and application results are compared foreach of the optical conditions. An apparatus structure according to thepresent embodiment is also the same as the structure shown in FIGS. 1 to4.

<Circuit Estimation Method for Sample>

Next, a circuit estimation method according to the present embodimentwill be described. According to the present embodiment, the circuitestimation is also performed according to the flow shown in FIG. 5. Thefollowing mainly describes processes different from the processesaccording to the first embodiment.

In step S30, a plurality of optical conditions are selected. Forexample, the user selects the plurality of optical conditions bychecking the check boxes of the plurality of optical conditions on theoptical condition selection screen 62 shown in FIG. 7 and touching theselection determination button 62 e.

In step S40, the electron beam is applied to the sample 23 sequentiallyunder the plurality of optical conditions thus selected. In step S50,the actual electron beam application result of the sample 23 is storedin the electron beam application result storage section 45 for each ofthe optical conditions.

In step S90, the actual electron beam application result and theestimated electron beam application result are compared for each of theoptical conditions. The comparator 34 generates a comparison result foreach of the optical conditions. In step S100, a determination is made asto whether each of the electron beam application results and acorresponding one of the estimated electron beam application resultscoincide with each other.

When a determination is made in step S100 that none of the plurality ofelectron beam application results coincides with the estimated electronbeam application results (No), the to-be-used-in-computation netlistsare updated in step S110. On the other hand, when a determination ismade that any one of the electron beam application results coincideswith a corresponding one of the estimated electron beam applicationresults (Yes), the process of step S120 is executed.

In step S120, the to-be-used-in-computation netlist stored in theto-be-used-in-computation netlist storage section 44 is stored in theestimated netlist storage section 47 as an estimated netlist. At thistime, the optical condition when the actual electron beam applicationresult and the estimated electron beam application result coincide witheach other may be stored together.

In step S130, measurement results for the plurality of opticalconditions may be displayed on the result display screen 70.

Main Effects of the Present Embodiment

According to the present embodiment, with one to-be-used-in-calculationdevice model and a plurality of optical conditions, the estimatedelectron beam application result and the actual electron beamapplication result are compared for each of the optical conditions. Thisconfiguration makes it is possible to increase accuracy in estimation ofthe electrical characteristics.

[Modification]

Note that the present embodiment is also applicable to a case where acomparison is made on the basis of the estimated netlist identified inthe first embodiment and a plurality of optical conditions. In thiscase, steps such as the selection of the to-be-used-in-calculationdevice model, the generation/update of the to-be-used-in-computationnetlist, and the identification of the to-be-used-in-computation netlistcan be omitted as appropriate.

This facilitates the estimation of the electrical characteristics of thesample whose netlist has been identified, and makes it possible toincrease accuracy in estimation.

Note that the present invention is not limited to the above-describedembodiments and includes various modifications. Further, some of thecomponents of one embodiment can be replaced with correspondingcomponents of another embodiment, and a component of another embodimentcan be added to the components of one embodiment. Further, it ispossible to add different components to the components of eachembodiment, delete some of the components of each embodiment, andreplace some of the components of each embodiment with differentcomponents. Note that each member and relative size shown in thedrawings have been simplified and idealized for easy understanding ofthe present invention, and the present invention may have a morecomplicated shape when being implemented.

1. A computing method of performing calculation related to a chargedparticle beam apparatus, the computing method comprising: a first stepof a processor storing, in a memory, a to-be-used-in-calculation devicemodel for use in estimation of a circuit of a sample and an opticalcondition under which a charged particle beam is applied to the sample;a second step of the processor storing, in the memory, a detectionsignal on a basis of secondary electrons emitted from the sample by anapplication of the charged particle beam applied to the sample under theoptical condition; and a third step of the processor generating ato-be-used-in-computation netlist on a basis of theto-be-used-in-calculation device model, estimating a first applicationresult when the charged particle beam is applied to the sample on abasis of the to-be-used-in-computation netlist and the opticalcondition, and comparing the first application result with a secondapplication result when the charged particle beam is applied to thesample on a basis of the optical condition.
 2. The computing methodaccording to claim 1, wherein the processor updates theto-be-used-in-calculation device model when the first application resultand the second application result differ from each other, and identifiesthe to-be-used-in-computation netlist as a netlist describing thecircuit of the sample when the first application result and the secondapplication result coincide with each other.
 3. The computing methodaccording to claim 2, wherein the processor changes a parameter valueincluded in the to-be-used-in-calculation device model, and updates theto-be-used-in-computation netlist using the parameter value changed. 4.The computing method according to claim 1, wherein the secondapplication result includes any one of the detection signal, aninspection image based on the detection signal, a brightness of theinspection image, and a brightness of each pixel of the inspectionimage.
 5. The computing method according to claim 1, wherein theto-be-used-in-calculation device model includes a model representing adefect in a device.
 6. The computing method according to claim 1,wherein the to-be-used-in-calculation device model includes any one of amodel defining a circuit of a device, a mathematical expression definingelectrical characteristics of the device, a shape of the device, andphysical properties of the device.
 7. The computing method according toclaim 6, wherein the to-be-used-in-calculation device model includes aparameter value of a circuit element included in the circuit of thedevice.
 8. The computing method according to claim 2, wherein theprocessor generates an inspection image on a basis of the detectionsignal, and generates a correspondence table that associates a positionof a plug electrode in the inspection image with each node in theto-be-used-in-computation netlist identified.
 9. The computing methodaccording to claim 1, further comprising a step of the processorstoring, in the memory, a pulse conversion condition under which thecharged particle beam is pulsed, wherein the processor estimates thefirst application result based on the optical condition, which controlsthe charged particle beam applied to the sample, and the pulseconversion condition.
 10. The computing method according to claim 1,wherein the processor compares, using a plurality of theto-be-used-in-calculation device models and one of the opticalconditions, the first application result and the second applicationresult for each of the to-be-used-in-calculation device models.
 11. Thecomputing method according to claim 1, wherein the processor compares,using one of the to-be-used-in-calculation device models and a pluralityof the optical conditions, the first application result and the secondapplication result for each of the optical conditions.
 12. A displayingmethod of outputting a display related to a charged particle beamapparatus, the displaying method comprising: a step of a processordisplaying a first application result and a second application result ona display, the first application result being estimated when a chargedparticle beam estimated from a to-be-used-in-computation netlist and anoptical condition is applied to a sample, the to-be-used-in-computationnetlist being generated based on the to-be-used-in-calculation devicemodel for use in estimation of a circuit of the sample, and the secondapplication result being estimated when the charged particle beam isapplied to the sample on a basis of the first application result and theoptical condition, wherein the display of the first application resultor the second application result includes at least one of a detectionsignal which is based on secondary electrons emitted from the sample byan application of the charged particle beam applied to the sample underthe optical condition; a waveform indicating the detection signal; aninspection image which is based on the detection signal; brightness ofthe inspection image; brightness of each pixel of the inspection image;an estimated netlist; and a circuit diagram.
 13. The displaying methodaccording to claim 12, wherein the display of the first applicationresult or the second application result includes at least one of theto-be-used-in-calculation device model for use in estimation of thecircuit of the sample, and the optical condition of the charged particlebeam applied to the sample.
 14. A computing method related to a chargedparticle beam apparatus, the computing method comprising: a step of aprocessor receiving, as a first input, an inspection result estimatedwhen a sample forming an electric circuit is inspected using aninspection tool; a step of the processor receiving, as a second input,an inspection result of the electric circuit obtained from a netlist ofthe electric circuit or a circuit model which is based on the netlist;and a step of the processor updating at least one of the netlist and thecircuit model according to the first input.